He knows

Rudra walked into the infirmary escorted by guards and stood from across his brothers bed as he gave him the same gentle old smile as the character of the old man had given time and time again, yet there was an uncanny spiciness to the smile this time which did not look innocent at all. 

Max did not smile back at the old man, yet he did not turn his head either. 

" My legs are weak, Ravan, tell your men to bring me a chair " Rudra said as he dropped the honorifics of the lord altogether and demanded that he be brought a chair. 

" Give me one good reason why I should not throw you in jail? " Max asked, however, his voice betrayed his pretence of sounding angry as his voice contained lots of traces of self doubt instead of an undertone of authority and anger. 

" You can't " Rudra replied calmly as he ascertained what Max already knew that he was much stronger than he appeared and that the Bloodfall clan was not strong enough to make him a captive.